I. Field of the Invention
The present invention relates to the field of gear profile checking devices, and more particularly to the field of gear profile checking devices which measure the contact between meshing gears. Even more particularly, the present invention relates to the field of gear profile checking devices which check the degree of contact between both faces of mating gears while the gears are rotating in a single direction.
II. Description of the Prior Art
Devices for checking the profile of gears have long been known. U.S. Pat. Nos. 1,198,637; 2,856,770; 3,774,313; and 3,952,418 are illustrative of the various types of devices used in the past to check gears. U.S. Pat. No. 1,198,637 discloses a device for angularly displacing one set of gears against another thereby inducing a tooth load between gear sets that is comparable to the load imposed between the gears when in normal operation. By displacing the gears one against another in a first direction a load pattern is imposed along one face of the gears to be checked. By angularly displacing the gear sets one to another in a second direction, the gears are loaded one against another along a second face of the gear teeth. By running the gear teeth for a period of time loaded first against one set of tooth faces and then for a period of time against the other set of tooth faces, inspection of the wear pattern between the faces of the gear teeth indicates whether a satisfactory tooth form has been established on the gear teeth. The testing is accomplished without employing the greater horse power and cost required to load the teeth by applying an input power to the shaft and absorbing the output power with a dynamometer. However the rotation must be stopped and the phase relationship between gears reversed to check the opposite gear tooth face.
U.S. Pat. No. 2,856,770 discloses an electromechanical apparatus for measuring the play or angular back lash in a transmission.
U.S. Pat. No. 3,774,313 discloses an apparatus for checking gear teeth profiles by measuring the radial movement of a plurality of master gears running in mesh with the gear to be checked. The master gears are loaded radially against the gear to be checked and have radially floating centers. By comparing the radial movement of the master gears center relative to each other, indication of the accuracy of the gear tooth profile is obtained. A flaw or indentation along the face of the gear can be detected by this device.
U.S. Pat. No. 3,952,418 discloses a master gear for checking tooth contact. The master gear has a plurality of electrical conducting surfaces along the contact area. Electrical potential is measured between the gear to be tested and the conducting surfaces to indicate the degree of contact between teeth.
None of the above listed patents disclose the features of the present invention which allow an angular relationship to be changed between rotating gears so that contact can be established on both faces of the gears without reversing rotation.
Differential gear sets such as those employed in the rear axle of automobiles have long been known. The present invention differs from conventional rear axle differentials in that all gears in the present invention rotate in a common plane or parallel planes.